Contact bridge

ABSTRACT

A contact bridge is disclosed which includes a tray-like structure having a bottom wall and a composite rim at the perimeter of the bottom wall. The structure is made from a bendable flat member consisting of a central portion and at least two margin strips integral with the central portion. The margin strips are bent along lines coincident with respective portions of the perimeter and configured to conjointly form the composite rim. Contact overlays are mounted on respective portions of the outer side of the bottom wall of the tray-like structure. The contact bridge is simple to manufacture and has a relatively high strength.

United States Patent [191 Seidel June 18, 1974 CONTACT BRIDGE Inventor: Siegfried Seidel, Amberg, Germany Assignee: Siemens Aktiengesellschaft,

Munchen, Germany [22] Filed: Dec. 11, 1972 [21] App]. No.: 313,997

[30] Foreign Application Priority Data Primary Examiner-Robert K. Schaefer Assistant Examiner-William J. Smith Attorney, Agent, or FirmKenyo'n & Kenyon Reilly Carr & Chapin [5 7] ABSTRACT A contact bridge is disclosed which includes a traylike structure having a bottom wall and a composite rim at the perimeter of the bottom wall. The structure vis made from a bendable flat member consisting of a central portion and at least two margin strips integral with the central portion. The margin strips are bent along lines coincident with respective portions of the perimeter and configured to conjointly form the composite rim. Contact overlays are mounted on respective portions of the outer side of the bottom wall of the tray-like structure. The contact bridge is simple to manufacture and has a relatively high strength.

16 Claims, 6 Drawing Figures CONTACT BRIDGE BACKGROUND OF THE INVENTION The invention relates to a tray-shaped contact bridge with contact overlays applied to the outside of the tray bottom.

Contact bridges of the kind mentioned above are disclosed in Deutsche Auslegeschrift Pat. No. 1,527,353; these contact bridges are generally made in a die press which is relatively expensive and virtually precludes making sharp edges at the bottom of the tray unless the strength is jeopardized. The sharp edges are needed to assure self-acting alignment of the contact overlyas when they are soldered on. In the known contact bridges, the wall of the tray is of the same thickness everywhere, so that after a relatively small number of switching cycles the edges of the tray melt through because of the occurrence of the are, if the contact bridge itself is not provided with a relatively large wall thickness at all tray walls. For this reason, experiments were conducted to make the tray-shaped contact bridges of non-ferrous metal castings to simply provide the end faces with a larger wall thickness. However, this configuration does not yet meet the desired requirements,

particularly with respect to cost and strength.

SUMMARY OF THE INVENTION It is an object of the invention to provide a trayshaped contact bridge which can be easily produced and which has a relatively high strength.

The invention then provides a tray-shaped contact bridge which is simple to manufacture and which has relatively high strength. According to the invention, the tray-shaped contact bridge of the type mentioned above is made utilizing a flat member, the wall of the tray being formed by bent-up strips of the flat member.

A feature of the contact bridge of the invention is a tray-like structure having a bottom wall and a composite rim at the perimeter of the bottom wall. The structure is made from a bendable flat member consisting of a central portion and at least two margin strips integral with the central portion. The margin strips are bent along lines coincident with respective portions of the perimeter and configured to conjointly form'the composite rim. Contact overlays are mounted on respective portions of the outer side of the bottom wall of the traylike structure.

A further increase in the strength of the contact bridge is obtained if the walls of the tray are formed by two side strips extending in the longitudinal direction of the flat member because then the end faces of the tray-shaped contact bridge can be made to have a curved configuration. Thus, according to a subsidiary feature of the invention, the central portion is longitudinally extended and defines a longitudinal axis. The margin strips can be two in number and extend in the direction of this axis. To these end faces, are burnoff pieces can be soldered advantageously, so that the separation point of the end face halves are covered over. A contact overlay protruding beyond the end faces can support the arc burnoff piece and can be soldered to it. The flat member can be sheared for this purpose at the separation line between the margin strips and the central portion. The shearing can advantageously also be made so that for the bent condition of the margin strips balcony-like projections of the flat member are provided outside the tray. Another feature of the invention therefore provides that the flat member is sheared determined distances along lines coincident with respective portions of the perimeter of the bottom wall of the tray-like structure so as to cause the longitudinal end regions of the central portion to extend out past the end faces to form balcony-like projections when the corresponding end portions of the margin strips are bent toward each other. The balcony-shaped projections themselves can serve as the arc burnolf piece, so that the resistance against material removal by the arc is increased.

According to a further feature of the invention, are burnoff pieces are mounted on the balcony-like projections so as to lie on the rim of the tray-like structure. Here, as also in the embodiment described above, the mass and the material of the arc bumoff pieces can be matched to the desired requirements independently of the strength of the contact bridge itself. An arc burnoff piece made of aluminum has been found advantageous, particularly in view of the reduced weight obtained therewith; this in turn reduces the tendency to chatter. The sharp-edged, balcony-shaped projection permits, in addition, the arc bumoff piece and the contact overlays to be soldered on in a simple manner because the sharp edges of the balcony-shaped projections effect a self-acting alignment of these parts in the soldering process. In the same soldering operation, the abutting ends of the margin strips can also be soldered together. It is not necessary to solder the burnoff pieces if they are force-lock held by being pressed against the balconyshaped projection by a contact pressure spring. This configuration permits replacement of the arc burnoff pieces, so that they, in turn, can be made smaller, commensurate with their weight and in view of the required service life. 1

Although the invention is illustrated and described herein as a contact bridge, it is nevertheless not intended to be limited to the details shown, since various modifications may be made therein within the scope and the range of the claims. The invention, however, together with additional objects and advantages will be best understood from the following description and in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the contact bridge of the invention are shown in the following FIGS. described below. Similar or like components are designated by the same reference numeral in each FIG. in which they appear.

FIG. 1 is a side elevation view of a contact bridge according to the invention and is equipped with a contact pressure leaf spring inserted therein. The view also shows on the right-hand side how the contact bridge can be provided with balcony-shaped projections according to a subsidiary embodiment.

FIG. 2 is a plan view from above of the contact bridge of FIG. 1 with the contact pressure spring removed.

FIG. 3 is a plan view from below of the contact bridge of FIG. 1 showing th contact overlays which are soldered to the tray-like structure.

FIG. 4 is a front view of the contact bridge of FIG. 1 taken at the left-hand side.

FIG. 5 is a plan view of the bendable flat member from which the tray-like structure of the contact bridge is made. The right-hand side of the view shows how the member must be sheared if the contact bridge is to have balcony-like projections.

FIG. 6 is a schematic perspective view, partially in section, of an alternate embodiment of the invention wherein the burnoff pieces are mounted on the traylike structure in tongue and groove fashion.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION The tray-shaped contact bridge shown in the drawing includes the tray bottom 1 and the tray Walls 2, 3, 4 and 5. In this embodiment, the contact overlays are soldered on at the outside of the tray bottom 1. A bar 8 between the contact overlays 6 and 7 is situated and has protrusions 9 which engage with cutouts 10 of the tray bottom. The bar is likewise soldered to the tray bottom. The bar 8 determines the spacing of the contact overlays 6 and 7 during the self-acting alignment and also takes over part of the current flow between the two contact overlays 6 and 7. A leaf spring II is inserted into the tray as shwon in FIG. 1. Balconylike projections I2 can be situated outside the tray walls 4 and S at the end faces of the contact bridge as shown on the right-hand side of the contact bridge in FIG. 1. The projections 12 serve on the one hand as the support surface for are burnoff pieces 13 and, on the other hand, as the sharp-edged support for the respective contact overlays 6 and 7 because if projections 12 are provided, they are also present here so that the contact overlays self-align on the edges of the projections 12. As shown in FIGS. 5 and 2, the walls of the tray are formed by two side strips 14 extending in the longitudinal direction of the contact bridge. The strips 14 are sheared at the points 15 and are turned in at the end zone of the flat part toward each other. The shear points are in the direction of the line between the side strip 14 and the central part 16. The shearing operation permits putting the gaps of the tray walls on the center axis of the contact bridge. The shear length is greater, if balcony-like projections 12 are provided, than in the other case, which is indicated on the left-hand side of FIGS. 1 to 5. The location of the side strips 14 in the bent condition is shown in FIG. 5 by dashed lines. Because the contact overlays are soldered to the contact bridge, practically no additional effort is required to solder the ends 17 of the side strips 14 together so that no gap remains. The contact overlays which extend beyond the edge (as exemplified by contact overlay 7), form the support for the arc burnoff pieces when no balcony-shaped projections 12 are provided. The burnoff pieces therefore can be soldered on in a simple manner.

FIG. 6 illustrated an alternate embodiment for mounting the burnoff pieces 18. Here, the burnoff pieces are each equipped with a slot-shaped recess 19 and can be pushed over the tray walls 4 and 5. The burnoff pieces have a step which serves as support for the contact pressure spring 11.

What is claimed is:

l. A conact bridge comprising a tray-like structure having a bottom wall and a composite rim at the perimspective portions of said perimeter and configured to conjointly form said composite rim, each of said margin strips having respective end portions, the end portions of said margin strips at the respective longitudinal end regions of said central portion being bent towards each other to form respective end faces of said structure, respective arc burnoff pieces mounted at said end faces, and contact overlays mounted on respective portions of the outer side of said bottom wall of said tray-like structure.

2. The contact bridge of claim 1 comprising a contact pressure spring configured so as to force-lock hold said burnoff pieces in place.

3. The contact bridge of claim 1, said burnoff pieces being soldered to said end faces respectively.

4. The contact bridge of claim 1, said contact overlays and said burnoff pieces being soldered to said traylike structure, and said margin strips being soldered to said central portion and to each other.

5. The contact bridge of claim 1, said burnoff pieces being made of aluminum.

6. The contact bridge of claim 1, each of said burnoff pieces having a groove for accommodating a corresponding one of said end faces therein.

7. The contact bridge of claim 6, said burnoff pieces having respective end walls facing each other, each of said end walls being provided with a step, and a contact pressure spring having respective ends and being mounted so as to be supported at said ends by respective ones of said steps.

8. The contact bridge of claim I, said contact overlays being mounted so as to project outwardly from said end faces respectively, said burnoff pieces being mounted on the projecting portions of said contact overlays respectively.

9. The contact bridge of claim 8, said burnoff pieces being soldered to said projecting portions of said contact overlays respectively.

10. The contact bridge of claim 1, each of said margin strips having respective end portions, the end portions of said margin strips at the respective longitudinal end regions of said central portion being bent toward each other to form respective end faces of said structure, said flat member being sheared determined dis tances along each of said lines so as to cause the longitudinal end regions of said central portion to extend out past said end faces to form balcony-like projections when said end portions are bent toward each other.

11. The contact bridge of claim 10 comprising respective arc burnoff pieces mounted on said projections so as to lie against corresponding ones of said end faces.

12. The contact bridge of claim 11 comprising a contact pressure spring configured so as to force-lock hold said burnoff pieces in place.

13. The contact bridge of claim ll, said contact overlays and said burnoff pieces being soldered to said traylike structure, and said margin strips being soldered to said central portion and to each other.

14. The contact bridge of claim 11, said burnoff pieces being made of aluminum.

15. The contact bridge of claim 10 comprising respective burnoff pieces mounted at corresponding ones of said end faces, each of said burnoff pieces having a groove for accommodating a corresponding one of said end faces therein.

16. The contact bridge of claim 15, said bumoff pieces having respective end walls facing each other, each of said end walls being provided with a step, and a contact pressure spring having respective ends and being mounted so as to be supported at said ends by re spective ones of said steps. 

1. A conact bridge comprising a tray-like structure having a bottom wall and a composite rim at the perimeter of the said bottom wall, said structure being made from a bendable flat member consisting of a central portion longitudinally extended and defining a longitudinal axis, and two margin strips integral with said central portion extending in the direction of said axis, said margin strips being bent along lines coincident with respective portions of said perimeter and configured to conjointly form said composite rim, each of said margin strips having respective end portions, the end portions of said margin strips at the respective longitudinal end regions of said central portion being bent towards each other to form respective end faces of said structure, respective arc burnoff pieces mounted at said end faces, and contact overlays mounted on respective portions of the outer side of said bottom wall of said tray-like structure.
 2. The contact bridge of claim 1 comprising a contact pressure spring configured so as to force-lock hold said burnoff pieces in place.
 3. The contact bridge of claim 1, said burnoff pieces being soldered to said end faces respectively.
 4. The contact bridge of claim 1, said contact overlays and said burnoff pieces being soldered to said tray-like structure, and said margin strips being soldered to said central portion and to each other.
 5. The contact bridge of claim 1, said burnoff pieces being made of aluminum.
 6. The contact bridge of claim 1, each of said burnoff pieces having a groove for accommodating a corresponding one of said end faces therein.
 7. The contact bridge of claim 6, said burnoff pieces having respective end walls facing each other, each of said end walls being provided with a step, and a contact pressure spring having respective ends and being mounted so as to be supported at said ends by respective ones of said steps.
 8. The contact bridge of claim 1, said contact overlays being mounted so as to project outwardly from said end faces respectively, said burnoff pieces being mounted on the projecting portions of said contact overlays respectively.
 9. The contact bridge of claim 8, said burnoff pieces being soldered to said projecting portions of said contact overlays respectively.
 10. The contact bridge of claim 1, each of said margin strips having respective end portions, the end portions of said margin strips at the respective longitudinal end regions of said central portion being bent toward each other to form respective end faces of said structure, said flat member being sheared determined distances along each of said lines so as to cause the longitudinal end regions of said central portion to extend out past said end faces to form balcony-like projections when said end portions are bent toward each other.
 11. The contact bridge of claim 10 comprising respective arc burnoff pieces mounted on said projections so as to lie against corresponding ones of said end faces.
 12. The contact bridge of claim 11 comprising a contact pressure spring configured so as to force-lock hold said burnoff pieces in place.
 13. The contact bridge of claim 11, said contact overlays and said burnoff pieces being soldered to said tray-like structure, and said margin strips being soldered to said central portion and to each other.
 14. The contact bridge of claim 11, said burnoff pieces being made of aluminum.
 15. The contact bridge of claim 10 comprising respective burnoff pieces mounted at corresponding ones of said end faces, each of said burnoff pieces having a groove for accommodating a corresponding one of said end faces therein.
 16. The contact bridge of claim 15, said burnoff pieces having respective end walls facing each other, each of said end walls being provided with a step, and a contact pressure spring having respective ends and being mounted so as to be supported at said ends by respective ones of said steps. 